Hierarchical Carbon-Nitrogen Architectures with Both Mesopores and Macrochannels as Excellent Cathodes for Rechargeable Li-O2 Batteries

Lithium-oxygen batteries are attracting more and more interest; however, their poor rechargeability and low efficiency remain critical barriers to practical applications. Herein, hierarchical carbon-nitrogen architectures with both macrochannels and mesopores are prepared through an economical and environmentally benign sol-gel route, showing high electrocatalytic activity and stable cyclability over 160 cycles as cathodes for Li-O-2 batteries. Such good performance owes to the coexistence of macrochannels and mesopores in C-N hierarchical architectures, which greatly facilitate the Li+ diffusion and electrolyte immersion, as well as provide an effective space for O-2 diffusion and O-2/Li2O2 conversion. Additionally, the mechanism of oxygen reduction reactions is discussed with the N-rich carbon materials through first-principles computations. The lithiated pyridinic N provides excellent O-2 adsorption and activation sites, and thus catalyzes the electrode processes. Therefore, hierarchical carbon-nitrogen architectures with both macrochannels and mesopores are promising cathodes for Li-O-2 batteries.